The present invention relates generally to a vortex tube and, in particular, a vortex generator for condensing condensible vapor.
Vortex tubes are well known. Typical vortex tubes are designed to operate with non-condensible gas such as air. A typical vortex tube turns compressed air into two air streams, one of relatively hot air and the other of relatively cold air. A common application for current vortex tubes is in air supply lines and other applications that utilize non-condensible gas under a high pressure.
A vortex tube does not have any moving parts. A vortex tube operates by imparting a rotational flow motion to the incoming compressed air stream. Directing compressed air into an elongated channel in a tangential direction does this.
FIGS. 12A and 12B illustrate vortex tubes of two known designs. FIG. 12A illustrates a counterflow vortex tube 200A in which a first outlet 202A is located proximate an inlet 206A, and a second outlet 204A (a substantially peripheral opening) is located at the opposite end.
FIG. 12B illustrates a uniflow vortex tube 200B in which both outlets 202B, 204B are located at the end opposite the inlet 206B. The operating principle of the uniflow vortex tube 200B is similar to the operation of the counterflow vortex tube 200A.
The general flow pattern inside a typical vortex tube 200 is shown. High-pressured or compressed gas enters the vortex tube tangentially at one end at inlet 206 and produces a strong vortex flow in the tube 200. A nozzle 208 is designed to direct the incoming gas in a tangential direction. One stream of gas is produced along the sidewall while a second stream of gas is produced along the longitudinal axis of the vortex tube 200A. Referring to FIG. 12A, the second outlet 204A communicates with the stream of gas that was produced along the outer wall; exiting air is relatively hotter than the compressed air that initially entered the vortex tube 200A. The first outlet 202A communicates with the steam of gas that was produced along the longitudinal axis. The air exiting the first outlet 202A is relatively cooler than the initial compressed air.
As the compressed gas enters the vortex tube 200A at inlet 206A, the velocity of fluid induces a vertical motion which creates a forced vortex at the center of the tube. This flow produces a pressure distribution along the radial direction. The gas proximate the sidewall of the vortex tube 200 is adiabatically compressed, thereby resulting in an increase in temperature. The work to compress the gas is produced by the gas near the longitudinal axis or centerline of the tube 200A, which is adiabatically expanded and cooled.
The cooler gas is confined to the center of the vortex tube substantially along the longitudinal axis and, in fact, creates a second vortex air stream within the initial vortex air stream but traveling in the opposite direction of the initial air stream. The inner vortex air stream of cooler gas leaves the vortex tube 200A along the axial direction of the vortex tube from an outlet 202A located near the first end of the vortex tube 200. The first or peripheral outlet 202A is positioned proximate the second end of the vortex tube 200A. The second or peripheral outlet 204A outlet provides an exit for the relatively hot gas. Accordingly, two separate air streams are produced at the respective outlets and the vortex tube 200A effectively separates a single air stream into a cold air stream and a hot air stream.
The total discharge (hot and cold) volume from a vortex tube is proportional to the absolute inlet pressure. Valves at the inlet (and in alternate embodiments at one or both outlets) control the air flow and, indirectly, the relative temperature gradients of the exiting gases.
In contrast with currently available vortex tubes, the present invention is referred to as a vortex generator in order to indicate that it is designed to operate on condensible vapor such as steam or a refrigerant vapor for use in a refrigeration apparatus.
The vortex generator of the present invention separates a high-pressure stream of condensible vapor into a relatively hot vapor component and a relatively cool liquid component. In contrast with current vortex tubes, there is no outlet for a cool stream.